(************************************************************************)
(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
(*   \VV/  **************************************************************)
(*    //   *      This file is distributed under the terms of the       *)
(*         *       GNU Lesser General Public License Version 2.1        *)
(************************************************************************)

(*i $Id: typeclasses_errors.ml 11282 2008-07-28 11:51:53Z msozeau $ i*)

(*i*)
open Names
open Decl_kinds
open Term
open Sign
open Evd
open Environ
open Nametab
open Mod_subst
open Topconstr
open Util
open Libnames
(*i*)

type contexts = Parameters | Properties

type typeclass_error = 
    | NotAClass of constr
    | UnboundMethod of global_reference * identifier located (* Class name, method *)
    | NoInstance of identifier located * constr list
    | UnsatisfiableConstraints of evar_defs * (evar_info * hole_kind) option
    | MismatchedContextInstance of contexts * constr_expr list * rel_context (* found, expected *)

exception TypeClassError of env * typeclass_error

let typeclass_error env err = raise (TypeClassError (env, err))

let not_a_class env c = typeclass_error env (NotAClass c)

let unbound_method env cid id = typeclass_error env (UnboundMethod (cid, id))

let no_instance env id args = typeclass_error env (NoInstance (id, args))

let unsatisfiable_constraints env evd ev = 
  let evd = Evd.undefined_evars evd in
    match ev with
    | None ->
	raise (TypeClassError (env, UnsatisfiableConstraints (evd, None)))
    | Some ev ->
	let evi = Evd.find (Evd.evars_of evd) ev in
	let loc, kind = Evd.evar_source ev evd in
	  raise (Stdpp.Exc_located (loc, TypeClassError
	    (env, UnsatisfiableConstraints (evd, Some (evi, kind)))))
	    
let mismatched_ctx_inst env c n m = typeclass_error env (MismatchedContextInstance (c, n, m))